Spin orbital torque via spin hall effect based energy assisted magnetic recording

ABSTRACT

A magnetic recording head includes a trailing shield, a main pole, and a spin Hall layer. The spin Hall layer is disposed between the trailing shield and the main pole. A first spin torque layer is disposed between the spin Hall layer and the trailing shield. A second spin torque layer is disposed between the spin Hall layer and the main pole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 16/453,986, filed Jun. 26, 2019, which is herein incorporatedby reference.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

Embodiments of the present disclosure generally relate to data storagedevices, and more specifically, to a magnetic media drive employing anenergy assisted write head based upon spin-orbital torque.

Description of the Related Art

Over the past few years, microwave assisted magnetic recording (MAMR)has been studied as a recording method to improve the areal density of amagnetic media device, such as a hard disk drive (HDD). One type of MAMRenabled magnetic recording is based on spin-transfer torque (STT).During operation, electrical current flows from the main pole to thetrailing shield through a field generation layer. Transmitted polarizedelectrons from a spin polarization layer and/or from reflected electronsare injected into the field generation layer causing switching orprecession of the magnetization of the field generation layer by spintransfer torque (STT) from the injected electrons. Switching orprecession of the magnetization of the field generation layer generatesan assisting field to the write field.

Another type of energy assisted magnetic recording is based onspin-orbital torque (SOT). During operation, charge current through aspin Hall layer generates a spin current in the spin Hall layer. Thespin orbital coupling of the spin Hall layer and a spin torque layer(STL) causes switching or precession of magnetization of the STL by thespin orbital coupling of the spin current from the spin Hall layer.Switching or precession of the magnetization of the STL can generate anassisting DC field or AC field to the write field. Energy assisted writeheads based on SOT have multiple times greater power efficiency incomparison to MAMR write heads based on STT.

FIG. 1 is one example of a cross-sectional view of an energy assistedwrite head 10 based on SOT. A SOT structure 50 is disposed between atrailing shield 40 and a main pole 20. The SOT structure 50 comprises aspin-torque layer (STL) 71 disposed below a spin Hall layer 52. Inmanufacturing the write head 10, the trailing shield 40, the main pole20, and the STL 71 are planarized by a lapping tool at a media facingsurface of the write head. The spin-torque layer 71 is formed to asufficient thickness 71T so that the spin-torque layer 72 remains afterplanarization since the uniformity and amount of planarization aredifficult to control. However, if the thickness 71T of the STL 70 thatremains after planarization is too large, switching of the magnetizationdirection of the STL 71 is low or none existent since SOT is a surfacephenomenon of the spin Hall layer 52 acting on the STL 71. A low ornon-existent switching of the magnetization direction of the STL resultsin generation of low or none existent assisting DC field. Therefore,there is a need for an improved energy assisted write head based on SOT.

SUMMARY OF THE DISCLOSURE

In one embodiment, a magnetic recording head includes a trailing shield,a main pole, and a spin Hall layer. The spin Hall layer is disposedbetween the trailing shield and the main pole. A first spin torque layeris disposed between the spin Hall layer and the trailing shield. Asecond spin torque layer is disposed between the spin Hall layer and themain pole.

In another embodiment, a magnetic recording head includes a trailingshield, a main pole, and a coil around the main pole. A spin Hall layeris disposed between the trailing shield and the main pole. Atrailing-shield-facing spin torque layer is disposed between the spinHall layer and the trailing shield. A main-pole-facing spin torque layeris disposed between the spin Hall layer and the main pole. The spin Halllayer is adapted to transmit a charge current in a cross-track directionbetween the trailing shield and the main pole.

In still another embodiment, a magnetic recording head includes atrailing shield, a main pole, and a spin Hall layer. The spin Hall layeris disposed between the trailing shield and the main pole. A first spintorque layer (STL) is disposed between the spin Hall layer and thetrailing shield. A second spin torque layer (STL) is disposed betweenthe spin Hall layer and the main pole. A first charge current blockinglayer is disposed between the first STL and the spin Hall layer. Asecond charge current blocking layer is disposed between the second STLand the spin Hall layer.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is one example of a cross-sectional view of an energy assistedwrite head based on SOT.

FIG. 2 is a schematic illustration of a data storage device such as amagnetic media device.

FIG. 3 is a fragmented, cross-sectional side view of a read/write headfacing the magnetic disk according to certain embodiments.

FIG. 4A is a schematic MFS view of certain embodiments of a portion of awrite head.

FIG. 4B is a fragmented, cross-sectional side view of certainembodiments of the write head along plane B-B of FIG. 4A.

FIG. 5A is a schematic MFS view of certain embodiments of a portion of awrite head.

FIG. 5B is a fragmented, cross-sectional side view of certainembodiments of the write head along plane C-C of FIG. 5A.

FIG. 6 is a schematic MFS view of certain embodiments of a SOTstructure.

FIG. 7 is a schematic MFS view of certain embodiments of a SOT structurehaving an STL comprising multiple layers of one or more ferromagneticmaterials.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

In the following, reference is made to embodiments of the disclosure.However, it should be understood that the disclosure is not limited tospecific described embodiments. Instead, any combination of thefollowing features and elements, whether related to differentembodiments or not, is contemplated to implement and practice thedisclosure. Furthermore, although embodiments of the disclosure mayachieve advantages over other possible solutions and/or over the priorart, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the disclosure. Thus, the followingaspects, features, embodiments and advantages are merely illustrativeand are not considered elements or limitations of the appended claimsexcept where explicitly recited in a claim(s). Likewise, reference to“the disclosure” shall not be construed as a generalization of anyinventive subject matter disclosed herein and shall not be considered tobe an element or limitation of the appended claims except whereexplicitly recited in a claim(s).

Embodiments relate to a magnetic media drive employing an energyassisted write head based upon spin-orbital torque (SOT). A magneticrecording or write head includes a first spin torque layer (STL) betweena spin Hall layer and a trailing shield and/or a second STL between aspin Hall layer and a main pole to produce an assisting DC field to arecording medium surface.

FIG. 2 is a schematic illustration of a data storage device such as amagnetic media device. Such a data storage device may be a singledrive/device or comprise multiple drives/devices. For the sake ofillustration, a single disk drive 100 is shown according to certainembodiments. As shown, at least one rotatable magnetic disk 112 issupported on a spindle 114 and rotated by a drive motor 118. Themagnetic recording on each magnetic disk 112 is in the form of anysuitable patterns of data tracks, such as annular patterns of concentricdata tracks (not shown) on the magnetic disk 112.

At least one slider 113 is positioned near the magnetic disk 112, eachslider 113 supporting one or more magnetic head assemblies 121 that mayinclude a spin Hall structure for generating SOT. As the magnetic disk112 rotates, the slider 113 moves radially in and out over the disksurface 122 so that the magnetic head assembly 121 may access differenttracks of the magnetic disk 112 where desired data are written. Eachslider 113 is attached to an actuator arm 119 by way of a suspension115. The suspension 115 provides a slight spring force which biases theslider 113 toward the disk surface 122. Each actuator arm 119 isattached to an actuator means 127. The actuator means 127 as shown inFIG. 2 may be a voice coil motor (VCM). The VCM includes a coil movablewithin a fixed magnetic field, the direction and speed of the coilmovements being controlled by the motor current signals supplied bycontrol unit 129.

During operation of the disk drive 100, the rotation of the magneticdisk 112 generates an air bearing between the slider 113 and the disksurface 122 which exerts an upward force or lift on the slider 113. Theair bearing thus counter-balances the slight spring force of suspension115 and supports slider 113 off and slightly above the disk surface 122by a small, substantially constant spacing during normal operation.

The various components of the disk drive 100 are controlled in operationby control signals generated by control unit 129, such as access controlsignals and internal clock signals. Typically, the control unit 129comprises logic control circuits, storage means and a microprocessor.The control unit 129 generates control signals to control various systemoperations such as drive motor control signals on line 123 and headposition and seek control signals on line 128. The control signals online 128 provide the desired current profiles to optimally move andposition slider 113 to the desired data track on disk 112. Write andread signals are communicated to and from write and read heads on theassembly 121 by way of recording channel 125.

The above description of a typical magnetic media device and theaccompanying illustration of FIG. 2 are for representation purposesonly. It should be apparent that magnetic media devices may contain alarge number of media, or disks, and actuators, and each actuator maysupport a number of sliders.

FIG. 3 is a fragmented, cross-sectional side view of a read/write head200 facing the magnetic disk 112 according to certain embodiments. Theread/write head 200 may correspond to the magnetic head assembly 121described in FIG. 1. The read/write head 200 includes a MFS 212, such asan air bearing surface (ABS), facing the disk 112, a magnetic write head210, and a magnetic read head 211. As shown in FIG. 3, the magnetic disk112 moves past the write head 210 in the direction indicated by thearrow 232 and the read/write head 200 moves in the direction indicatedby the arrow 234.

In some embodiments, the magnetic read head 211 is a magnetoresistive(MR) read head that includes an MR sensing element 204 located betweenMR shields S1 and S2. In other embodiments, the magnetic read head 211is a magnetic tunnel junction (MTJ) read head that includes a MTJsensing element 204 located between MR shields S1 and S2. The magneticfields of the adjacent magnetized regions in the magnetic disk 112 aredetectable by the MR (or MTJ) sensing element 204 as the recorded bits.

The write head 210 includes a main pole 220, a leading shield 206, atrailing shield 240, a spin orbital torque (SOT) structure 250, and acoil 218 that excites the main pole 220. The coil 218 may have a“pancake” structure which winds around a back-contact between the mainpole 220 and the trailing shield 240, instead of a “helical” structureshown in FIG. 3. The SOT structure 250 is formed in a gap 254 betweenthe main pole 220 and the trailing shield 240. The main pole 220includes a trailing taper 242 and a leading taper 244. The trailingtaper 242 extends from a location recessed from the MFS 212 to the MFS212. The leading taper 244 extends from a location recessed from the MFS212 to the MFS 212. The trailing taper 242 and the leading taper 244 mayhave the same degree of taper, and the degree of taper is measured withrespect to a longitudinal axis 260 of the main pole 220. In someembodiments, the main pole 220 does not include the trailing taper 242and the leading taper 244. Instead, the main pole 220 includes atrailing side (not shown) and a leading side (not shown), and thetrailing side and the leading side are substantially parallel. The mainpole 220 may be a magnetic material such as a FeCo alloy. The leadingshield 206 and the trailing shield 240 may be a magnetic material, suchas NiFe alloy.

FIG. 4A is a schematic MFS view of certain embodiments of a portion of awrite head 210, such as the write head of FIG. 3 or other suitablemagnetic media drives. FIG. 4B is a fragmented, cross-sectional sideview of certain embodiments of the write head 210 along plane B-B ofFIG. 4A. As shown in FIGS. 4A-B, the write head 210 includes a SOTstructure 250 between a trailing shield 240 and a main pole 220 having atrailing taper. As shown in FIG. 4A, the write head 210 further includesside shields 302 sandwiching the main pole 220 along the cross-trackdirection and a leading shield 206 in a track direction. The sideshields 302 can be in direct contact with the leading shield 206 and thetrailing shield 240.

The SOT structure 250 comprises a spin Hall layer 252, a firstspin-torque layer (STL) 271 proximate between the spin Hall layer 252and the trailing shield 240, and a second STL 272 between the spin Halllayer 252 and the main pole 220. The first STL 271 can also be referredto as a trailing-shield-facing STL, and the second STL 272 can also bereferred to as a main-pole-facing STL.

The spin Hall layer 252 comprises a heavy metal, such as beta phasetungsten (β-W), beta phase Tantalum (β-Ta), platinum (Pt), hafnium (Hf),a heavy metal alloy of tungsten with hafnium, and/or iridium, an alloyof tellurium (Te) with bismuth (Bi) and/or antimony (Sb), bismuth dopedcopper, antiferromagnetic materials, and multiple layers thereof.Examples of antiferromagnetic materials include MnIr, XMn (X=Fe, Pd, Ir,and Pt), and other Cu—Au—I type antiferromagnets. In certainembodiments, the spin Hall layer 252 is formed to a thickness 252T (FIG.4B) from about 3 nm to about 8 nm.

In certain embodiments, the STLs 271, 272 each comprise a negativemagnetic anisotropy constant (K_(u)) material. An example of a negativeK_(u) STL are one or more layers of CoFe, CoIr, NiFe, or CoFeX alloywherein X=B, Ta, Re, Ir. In certain embodiments, the STLs 271, 272 eachcomprises one or more layers of CoFe. The STLs 271, 272 can be the sameor different negative K_(u) materials. A negative K_(u) STL switchesin-plane under influence from spin-orbital torque from a spin Halllayer. In certain embodiments, each STL 271, 272 is formed to athickness 271T, 272T from about 3 nm to about 5 nm.

During operation, a charge current flows through the spin Hall layer 252generating SOT. The SOT generated by the spin Hall layer 252 inducesmagnetization switching of magnetization of the STLs 271, 272. In someembodiments, the SOT structure 250 has an effective spin injectionefficiency (β) of about 0.3 to 0.6, about 2 to 6 times larger than thatof a head using a SST pseudo spin-valve structure (having an effectivespin injection efficiency (β) of about 0.1 to 0.3). Higher effectivespin injection efficiency leads to reduced critical switching currentdensity, which is defined by the equation (1):

$\begin{matrix}{J_{C\; 0} \approx {\frac{2e}{\hslash}\mu_{0}M_{S}t\;{{\alpha\left( {H_{C} + {M_{eff}/2}} \right)}/\beta}}} & (1)\end{matrix}$Based on equation (1), the 2 to 6 times increase in effective spininjection efficiency (β) for the SOT based head leads to a reduction ofthe critical switching current density by 2 to 6 times, which in turnbrings a higher energy efficiency. Furthermore, the strong SOT generatedby the spin Hall layer 252 enforces in-plane magnetization oscillationin the STLs 271, 272, and the strong SOT utilizes less current flowingthrough the spin Hall layer 252, leading to improved reliability due toless joule heating.

As shown in FIG. 4B, the magnetization direction 220M of the main pole220 and the magnetization direction 240M of the trailing shield 240 isdetermined by the coil 218 (FIG. 3) around the body of the main pole220. The direction of the charge current 218J is shown schematically bya dot representing charge current coming out of the plane of the figureand an X representing charge current coming into the plane of thefigure. A write field 280 is generated between the main pole 230 and thetrailing shield 240 acting as a return pole.

A charge current 252J directed through the spin Hall layer 252 in adirection represented by an X into the plane of the figure results in aswitching of the magnetization in a general direction 271M of the firstSTL 271 and results in a switching of the magnetization in a generaldirection 272M of the second STL 272. The magnetization direction 271Mof the first STL 271 is pointed in generally the same direction as themagnetization direction 240M of the trailing shield 240. Themagnetization direction 272M of the second STL 272 is generally pointedin the same direction as the magnetization direction 220M of the mainpole 220. A DC magnetic field 282 is generated by the STLs 271, 272pointed generally the same direction as the write field 280.

In certain embodiments, as shown in FIG. 4B, the spin Hall layer 252,the first STL 271, and the second STL 272 form a flat surface at a mediafacing surface of the write head 210 so that the SOT structure 250 canbe close to a recording medium. In certain embodiments, as shown in FIG.4B, the spin Hall layer 252, the first STL 271, the second STL 272, thetrailing shield 240, and the main pole 220 form a flat surface at amedia facing surface of the write head so that the write head can beclose to a recording medium surface.

FIG. 5A is a schematic MFS view of certain embodiments of a portion ofthe write head 210 of FIG. 4A with a charge current 252J flowing in thereverse direction. FIG. 5B is a fragmented, cross-sectional side view ofcertain embodiments of the write head 210 along plane C-C of FIG. 5A.

As shown in FIG. 5B, the direction of the charge current 218J of thecoil 218 is reversed in comparison to FIG. 4B resulting in reversing themagnetization direction 220M of the main pole 220 and the magnetizationdirection 240M of the trailing shield 240 and reversing the direction ofthe write field 280. The direction of the charge current 252J directedthrough the spin Hall layer 252 is reversed in comparison to FIG. 4Bresulting in reversing the direction of the DC magnetic field 282 to bepointed in generally the same direction as the write field 280.

As shown in FIGS. 4A-B, 5A-B, the SOT structure 250 comprises the spinHall layer 252 in direct contact with the first STL 271 and the secondSTL 272 in certain embodiments. In certain embodiments, the spin Halllayer 252 can comprise a material that has a higher charge conductivitythan the first STL 271 and the second STL 272 to reduce charge currentshunting through the first STL 271 and the second STL 272.

FIG. 6 is a schematic MFS view of certain embodiments of a SOT structure250 comprises one or more intervening layers between the spin Hall layer252 and each STLs 271, 272. The spin Hall layer 252 can comprise amaterial that has a lower or higher charge conductivity than the firstSTL 271 and the second STL 272. The SOT structure 250 comprises a firstcharge current blocking layer 276 between a first STL 271 and a spinHall layer 252 and a second charge current blocking layer 277 between asecond STL 272 and the spin Hall layer 252. The first and second chargecurrent blocking layers 276, 277 comprise a material that is a goodcharge current insulator but a good spin current conductor. Materialsthat are a good charge current insulator but a good spin currentconductor include magnesium oxide, yttrium iron garnet, and othersuitable materials. The charge current blocking layers 276, 277 reduceor prevent the charge current through the spin Hall layer 252 fromelectrically shunting through the STLs 271, 272. If charge current isshunted through the STLs 271, 272, then less spin current will begenerated by the spin Hall layer 252. In certain embodiments, the firstcharge current blocking layer 276 and the second charge current blockinglayer 277 are each formed to a thickness 276T, 277T from about 0.5 nm toabout 1.5 nm

FIG. 7 is a schematic MFS view of certain embodiments of a SOT structure250 having an STL 271 comprising multiple layers 271 of one or moreferromagnetic materials. Although three layers 271 are shown in FIG. 7,the STL 271 can comprise of two or more layers 271. The ferromagneticmultiple layers 271 can be ferromagnetic materials of an anisotropy(positive or negative). Each of the ferromagnetic multiple layers 271can comprise the same or different ferromagnetic materials. In certainembodiments, the ferromagnetic multiple layers 271 comprises the samenegative anisotropy ferromagnetic material. The multiple layers 271 canprovide increased in-plane switching in comparison to a bulk STL layer.The multiple layers 271 do not require any intervening layers betweenthe multiple layers 271 to provide increased in-plane switching.Although the SOT structure 250 in FIG. 7 is shown as including one STL271, the SOT structure 250 may further include another STL.

The write heads 210 of FIGS. 3, 4A-B, and 5A-B may further compriseother components. For example, the gap 254 surrounding the main pole 220may be filled with a dielectric material. In another example, thetrailing shield 240 may further comprises a trailing shield hot seedlayer proximate to the SOT structure 250.

The SOT structures 250 of FIGS. 4A-B, 5A-B, and 6 have been described ashaving a SOT structure 250 comprising a first STL 271 facing thetrailing shield 240 and a second STL 272 facing the main pole 220 incertain embodiments. In other embodiments, the SOT structure 250comprises a single STL. For example, in certain embodiments, the SOTstructure comprising just a trailing-shield-facing STL between a spinHall layer and a trailing shield without another STL. For example, inanother embodiment, the SOT structure comprising just a main-pole-facingSTL between a spin Hall layer and a main-pole without another STL.

As shown in FIGS. 4A-B, 5A-B, a SOT structure 250 without any chargecurrent blocking layers comprises a first STL 271 between a spin Halllayer 252 and a trailing shield 240 and a second STL 272 between thespin Hall layer 252 and the main pole 220. The first STL 271 and/or thesecond STL 272 can be each formed to a thickness 271T, 272T of about 5nm or less in certain embodiments. As shown in FIG. 6, a SOT structure250 comprises a first STL 271 between a spin Hall layer 252 and atrailing shield 240 and a second STL 272 between the spin Hall layer 252and the main pole 220. A charge current blocking layers 276 is betweenthe first STL 271 and the spin Hall layer 252 and a charge currentblocking layer 277 is between the second STL 272 and the spin Hall layer252. In certain embodiments, the total thickness 278T of the first STL271 with the charge current blocking layers 276 and/or the totalthickness 279T of the second STL 272 with the charge current blockinglayers 277 can be about 5 nm or less. As shown in FIG. 7, a SOTstructure 250 having a STL 271 formed from multiple layers 271 can beformed to a total thickness 278T with or without a charge currentblocking layer 276 of about 5 nm or less. Without being bound by theoryunless specifically set forth in the claims, it is believed that adistance of about 5 nm is the magnetic exchange length for SOT from thespin Hall layer 252 to the STL 271 since SOT is a surface phenomenon ofthe spin Hall layer 252. Although a thicker STL than the magneticexchange length can be used, only a portion of the STL proximate thespin Hall layer 252 will experience SOT. As a result, the magneticswitching of the thicker STL will not be possible.

In certain embodiments, a length 271L, 272L of the STLs 271, 271 ofFIGS. 4A-B, 5A-B, 6, and 7 can be made to any suitable dimension sincethis dimension is less impacted by planarization of the write head incomparison to the planarization of the write head of FIG. 1. In certainembodiments, the length 271L, 272L is formed to a dimension of about 30nm or more, such as about 30 nm to about 60 nm.

In certain embodiments, a negative magnetic anisotropy constant (K_(u))material between a spin Hall layer and trailing shield and/or between aspin Hall layer and main pole generates a greater assisting magneticfield at a recording medium surface due to its in-plane switching incomparison of out-of-plane switching of positive magnetic anisotropyconstant (Ku) materials. A SOT structure with a STL of a positivemagnetic anisotropy constant (Ku) material with out-of-plane switchingmay cause an adverse shunting effect of the write field between the mainpole 220 and the trailing shield.

Embodiments relate to a magnetic media drive employing an energyassisted write head based upon spin-orbital torque (SOT). A magneticrecording or write head includes a first spin torque layer (STL) betweena spin Hall layer and a trailing shield and/or a second STL between aspin Hall layer and a main pole to produce an assisting DC field to arecording medium surface. In certain aspects, the SOT structure canplanarized in a manufacturing environment without inadvertently removingor over planarizing the STL.

In one embodiment, a magnetic recording head includes a trailing shield,a main pole, and a spin Hall layer. The spin Hall layer is disposedbetween the trailing shield and the main pole. A first spin torque layeris disposed between the spin Hall layer and the trailing shield. Asecond spin torque layer is disposed between the spin Hall layer and themain pole.

In another embodiment, a magnetic recording head includes a trailingshield, a main pole, and a coil around the main pole. A spin Hall layeris disposed between the trailing shield and the main pole. Atrailing-shield-facing spin torque layer is disposed between the spinHall layer and the trailing shield. A main-pole-facing spin torque layeris disposed between the spin Hall layer and the main pole. The spin Halllayer is adapted to transmit a charge current in a cross-track directionbetween the trailing shield and the main pole.

In still another embodiment, a magnetic recording head includes atrailing shield, a main pole, and a spin Hall layer. The spin Hall layeris disposed between the trailing shield and the main pole. A first spintorque layer (STL) is disposed between the spin Hall layer and thetrailing shield. A second spin torque layer (STL) is disposed betweenthe spin Hall layer and the main pole. A first charge current blockinglayer is disposed between the first STL and the spin Hall layer. Asecond charge current blocking layer is disposed between the second STLand the spin Hall layer.

EXAMPLES

A perpendicular magnetic recording write head without a SOT or a MAMRstructure (referred to in the examples as a “PMR”) and an energyassisted recording write head based on SOT of FIGS. 4A-B, 5A-B (referredto in the examples as “SOT”) were modeled. The SOT write head wasmodeled to have a STL with a saturation magnetization (M_(s)) of 2.2 T.The write heads were each modelled to have a magnetic core width of 58nm as the magnetic flux footprint to a magnetic recording medium. Theproperties of the modelled write heads are shown in TABLE 1.

TABLE 1 Write H_(eff) H_(grad) xH_(gard) Curv. OW gain BPI gain Head(Oe) (Oe/nm) (Oe/nm) (nm) (db) (%) PMR 9784 270 159.3 5.69 ref. ref. SOT9926 315 160.4 5.16 1 5

As shown in TABLE 1, the SOT write head had a higher effective magneticfield (H_(eff)), a higher magnetic field gradient in the down trackdirection (H_(grad)), a higher magnetic field gradient in thecross-track direction (xH_(gard)), a lower transition curvature, awrite-ability (OW) gain, and a greater bits per inch (BPI) gain than aPMR head.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A magnetic recording head, comprising: a trailing shield; a main pole; a spin Hall layer between the trailing shield and the main pole; and a spin torque layer (STL) between the spin Hall layer and the trailing shield, the STL comprising a negative magnetic anisotropy material.
 2. The magnetic recording head of claim 1, wherein the STL has a thickness from about 3 nm to about 5 nm.
 3. The magnetic recording head of claim 1, wherein the spin Hall layer comprises a heavy metal selected from a group consisting of beta phase tungsten (β-W), beta phase tantalum (β-Ta), platinum (Pt), hafnium (Hf), an alloy of tungsten, an alloy of tellurium (Te), bismuth doped copper, antiferromagnetic materials, and multiple layers thereof.
 4. The magnetic recording head of claim 1, wherein a thickness of the spin Hall layer is from about 3 nm to about 8 nm.
 5. The magnetic recording head of claim 1, wherein the spin Hall layer and the STL form a flat surface at a media facing surface of the magnetic recording head.
 6. The magnetic recording head of claim 1, wherein the spin Hall layer, the STL, the trailing shield, and the main pole form a flat surface at a media facing surface of the magnetic recording head.
 7. The magnetic recording head of claim 1, further comprising: a first charge current blocking layer between the STL and the spin Hall layer and the trailing shield; and a second charge current blocking layer between the spin Hall layer and the trailing shield.
 8. The magnetic recording head of claim 1, further comprising a charge current blocking layer between the STL and the spin Hall layer, the charge current blocking layer comprising a material that is a charge current insulator and a spin current conductor, wherein the charge current blocking layer has a thickness from about 0.5 nm to about 1.5 nm.
 9. A magnetic media drive, comprising: a magnetic recording head, comprising: a trailing shield; a main pole; a spin Hall layer between the trailing shield and the main pole; and a spin torque layer (STL) between the spin Hall layer and the trailing shield, the STL comprising a negative magnetic anisotropy material.
 10. A magnetic recording head, comprising: a trailing shield; a main pole; a coil around the main pole: a spin Hall layer between the trailing shield and the main pole; and a trailing-shield-facing spin torque layer (STL) between the spin Hall layer and the trailing shield, wherein the spin Hall layer is adapted to transmit a charge current in a cross-track direction between the trailing shield and the main pole.
 11. The magnetic recording head of claim 10, wherein the coil is adapted to excite the main pole in a main pole magnetization direction and to excite the trailing shield in a trailing shield magnetization direction.
 12. The magnetic recording head of claim 10, wherein the spin Hall layer is adapted to transmit a spin orbital torque to switch a magnetization of the trailing-shield-facing STL in a direction similar to a trailing shield magnetization direction.
 13. The magnetic recording head of claim 10, wherein the spin Hall layer is adapted to transmit a spin orbital torque to cause in-plane switching of a magnetization direction of the trailing-shield-facing STL.
 14. The magnetic recording head of claim 13, wherein the in-plane switching of the magnetization direction of the trailing-shield-facing STL generates a DC field in a same direction as a write field between the main pole and the trailing shield.
 15. The magnetic recording head of claim 10, wherein the spin Hall layer comprises beta phase tungsten (β-W), beta phase Tantalum (β-Ta), platinum (Pt), or combinations thereof.
 16. The magnetic recording head of claim 10, wherein the trailing-shield-facing STL comprises a negative magnetic anisotropy material.
 17. A magnetic media drive, comprising: a magnetic recording head, comprising: a trailing shield; a main pole; a coil around the main pole: a spin Hall layer between the trailing shield and the main pole; and a trailing-shield-facing spin torque layer (STL) between the spin Hall layer and the trailing shield, wherein the spin Hall layer is adapted to transmit a charge current in a cross-track direction between the trailing shield and the main pole.
 18. A magnetic recording head, comprising: a trailing shield; a main pole; a spin Hall layer between the trailing shield and the main pole; a spin torque layer (STL) between the spin Hall layer and the trailing shield; and a charge current blocking layer between the STL and the spin Hall layer.
 19. The magnetic recording head of claim 18, wherein the charge current blocking layer comprises a material that is a charge current insulator and a spin current conductor.
 20. The magnetic recording head of claim 18, wherein the charge current blocking layer comprises a material selected from a group consisting of magnesium oxide and yttrium iron garnet.
 21. The magnetic recording head of claim 18, wherein the charge current blocking layer has a thickness from about 0.5 nm to about 1.5 nm.
 22. The magnetic recording head of claim 18, wherein the spin Hall layer comprises beta phase tungsten (β-W), beta phase Tantalum (β-Ta), platinum (Pt), or combinations thereof, and wherein the STL comprises one or more layers of CoFe, CoIr, NiFe, CoFeX alloy wherein X is chosen from B, Ta, Re, Ir, or combinations thereof.
 23. A magnetic media drive, comprising: a magnetic recording head, comprising: a trailing shield; a main pole; a spin Hall layer between the trailing shield and the main pole; a spin torque layer (STL) between the spin Hall layer and the trailing shield; and a charge current blocking layer between the STL and the spin Hall layer. 